Electric lamp an dlamp base

ABSTRACT

An electric lamp has a lamp vessel ( 1 ) and is provided with an illumination source ( 2 ). A central current-supply conductor ( 3 ) and a side current-supply conductor ( 4 ) issue from the lamp vessel. The electric lamp has a lamp base ( 5 ) for providing a mechanical connection of the lamp vessel and for providing a mechanical and electrical connection of the current-supply conductors. At a side facing the lamp vessel, the lamp base is provided with a notch ( 6 ) for passing through the side current-supply conductor. At a side facing away from the lamp base, the side current-supply conductor is provided with a coagulated droplet of material of the side current-supply conductor. Preferably, the coagulated droplet is made by laser heating of a portion of the side current-supply conductor issuing from the notch. According to the invention, the side current-supply conductor is reliably connected to the lamp base while soldering is dispensed with.

The invention relates to the basing of electric lamps.

In addition, the invention relates to a lamp base for use in an electriclamp.

Electric lamps generally comprise a lamp vessel closed in a gastightmanner, the lamp vessel being provided with an illumination source. Theillumination source may be, for example, a (tungsten) incandescent bodyprovided in the lamp vessel, which may be a halogen lamp vessel, or ahalogen burner provided in the lamp vessel. In addition, theillumination source may be a metal halide lamp provided in the glassvessel.

Electric lamps of the kind mentioned in the opening paragraph are wellknown in the art. The known electric lamp comprises a centralcurrent-supply conductor and a side current-supply conductor, whichconductors issue from the lamp vessel. In addition, the electric lampsare provided with a lamp base, also denoted lamp cap. The lamp basenormally comprises an externally threaded sheet-metal shell. The lampbase of an electric lamp generally provides a mechanical and electricalconnection of the central current-supply conductor and the sidecurrent-supply conductor.

The central current-supply conductor and the side current-supplyconductor are normally connected to the lamp base by soldering.Soldering is a well-known technology. Commonly employed solder materialsare alloys of lead.

A disadvantage of the known electric lamp is that the material used inthe soldering process may have toxic aspects. Future regulations maystipulate lead-free soldering.

The invention has for its object to eliminate the above disadvantagewholly or partly. According to the invention, an electric lamp of thekind mentioned in the opening paragraph for this purpose comprises:

a lamp vessel closed in a gastight manner and provided with anillumination source,

a central current-supply conductor and a side current-supply conductorissuing from the lamp vessel,

a lamp base for providing a mechanical connection of the lamp vessel andfor providing a mechanical and electrical connection of the centralcurrent-supply conductor and the side current-supply conductor,

the lamp base being provided with a notch for passing through the sidecurrent-supply conductor at a side facing the lamp vessel,

the side current-supply conductor being provided with a coagulateddroplet of material of the side current-supply conductor at a sidefacing away from the lamp base.

An advantage of the electric lamp according to the invention is that theside current-supply conductor in the notch of the lamp base and thecoagulated droplet of material of the side current-supply conductorprovide a reliable mechanical and electrical connection to the lampbase. Soldering is thus avoided in the electric lamp according to theinvention.

To further enhance the mechanical and electrical contact between theside current-supply conductor and the lamp base, the coagulated dropletis preferably in contact with the lamp base.

Preferably, the coagulated droplet is made by laser heating of a portionof the side current-supply conductor issuing from the notch in the lampbase. The laser melts the side current-supply conductor, and a dropletof molten material travels in the direction of the notch in the lampbase. When the droplet of molten material touches the lamp base at thelocation of the notch, the heat in the droplet is dissipated in thematerial of the lamp base. As a consequence, the droplet solidifies atthe location of the notch in the lamp base.

Preferably, the side current-supply conductor is made from monel wire.Monel wire is a well-known material used for current-supply conductorsin electric lamps. A suitable material for the lamp base is aluminum.

A preferred embodiment of the electric lamp according to the inventionis characterized in that the side current-supply conductor is inclamping engagement with the notch in the lamp base. The clampingengagement further enhances the mechanical and electrical contactbetween the side current-supply conductor and the lamp base.

Preferably, the notch in the lamp base is wedge-shaped. The mechanicaland electrical contact between the side current-supply conductor and thelamp base is improved when a wedge-shape notch is used.

Preferably, the notch is provided in the lamp base by means of lasercutting. The shape, in particular the wedge shape of the notch in thelamp base can be provided relatively easily by means of laser cutting.

The invention will now be elucidated in more detail with reference to anumber of embodiments and a drawing, in which:

FIG. 1A is a perspective view of an electric lamp according to anembodiment of the invention, and

FIG. 1B is a perspective view of a detail of the lamp base of theelectric lamp according to an embodiment of the invention.

The Figures are purely diagrammatic and not drawn true to scale. Somedimensions are particularly strongly exaggerated for reasons of clarity.Equivalent components have been given the same reference numerals asmuch as possible in the Figures.

FIG. 1A is a schematic, partly perspective view of an electric lampaccording to an embodiment of the invention. FIG. 1B is a schematic,partly perspective view of a detail of the lamp base of the electriclamp according to an embodiment of the invention. The electric lampcomprises a lamp vessel 1 closed in a gastight manner and provided withan illumination source 2. In the example of FIG. 1A, the illuminationsource 2 is a (tungsten) incandescent body. In an alternativeembodiment, the illumination source is a halogen burner provided in thelamp vessel. In a further embodiment, the illumination source may be ametal halide lamp provided in the glass vessel.

The illumination source 2 is provided with a central current-supplyconductor 3 and a side current-supply conductor 4. The centralcurrent-supply conductor 3 and a side current-supply conductor 4 issuefrom the lamp vessel 1 (not shown in FIG. 1A).

The electric lamp in FIG. 1A is provided with a lamp base 5, alsodenoted lamp cap. The lamp base normally comprises an externallythreaded sheet-metal shell having one end enclosed with a ring 15 ofinsulation material (for example a glass). The ring 15 is provided witha central aperture communicating with the interior of the shell.Normally the central current-supply conductor 3 is electricallyconnected to the central aperture in the ring 15.

The electric lamp in FIG. 1A is a typical Edison screw type lamp. Thelamp base 5 generally provides the mechanical connection of the lampvessel 1. In addition, the lamp base 5 provides the mechanical andelectrical connection of the central current-supply conductor 3 and theside current-supply conductor 4 to the exterior.

According to the invention, the lamp base 5 is provided, at a sidefacing the lamp vessel 1, with a notch 6 for passing through the sidecurrent-supply conductor 3. In addition, the side current-supplyconductor 4 is provided with a coagulated droplet 7 of material of theside current-supply conductor 4 at a side facing away from the lamp base5. The notch 6 in the lamp base 5 carrying the side current-supplyconductor 4 is shown in detail in FIG. 1B. The side current-supplyconductor 4 in the notch 6 of the lamp base 5 and the coagulated droplet7 of material of the side current-supply conductor 4 provide a reliablemechanical and electrical connection to the lamp base. A reliableconnection is realized while soldering is dispensed with. To furtherenhance the mechanical and electrical contact between the sidecurrent-supply conductor 4 and the lamp base 5, the coagulated droplet 7preferably makes contact with the lamp base.

The coagulated droplet 7 is preferably made by laser heating. To thisend a portion of the side current-supply conductor 4 issuing from thenotch 6 in the lamp base 5 is heated by a laser pulse. The laser meltsthe side current-supply conductor 4, thus creating a droplet of moltenmaterial. The droplet of molten material travels in the direction of thenotch in the lamp base. When the droplet of the molten material touchesthe lamp base 5 at the location of the notch 6, the heat in the dropletis dissipated in the material of the lamp base 5. As a consequence, thedroplet solidifies at the location of the notch in the lamp base,thereby forming the coagulated droplet 7.

The side current-supply conductor 4 is preferably made from monel wire.Monel wire is a well-known material used for current-supply conductorsin electric lamps. Monel wire comprises 60-70% Ni, 25-35% Cu, 3% Mn, 1%Fe, and 1% Si. A suitable lamp base material is aluminum.

Preferably, the side current-supply conductor 4 is in clampingengagement with the notch 6 in the lamp base 5. The clamping engagementfurther enhances the mechanical and electrical contact between the sidecurrent-supply conductor and the lamp base. The notch 6 in the lamp base5 as shown in FIG. 1B is wedge-shaped. The side current-supply conductorcan be pulled into the notch, for example under the influence of acertain force, thereby enhancing the mechanical and electrical contactbetween the side current-supply conductor and the lamp base.

The notch 6 is preferably provided in the lamp base 5 by means of lasercutting. The shape, in particular the wedge shape of the notch 6 in thelamp base 5, can be provided relatively easily by means of lasercutting. In addition, the lamp base 5 generally also has a spiral shapein the vicinity of the rim, which makes conventional cutting or sawingrather complicated. Since the material of the lamp base is relativelysoft, it is in addition difficult to machine the lamp base withoutdistorting the rim of the lamp base.

The electric lamp according to the invention provides a reliableconnection of the side current-supply conductor to the lamp base.Soldering of the side current-supply conductor 4 to the lamp base 5 canbe dispensed with.

It should be noted that the above-mentioned embodiments illustraterather than limit the invention, and that those skilled in the art willbe able to design many alternative embodiments without departing fromthe scope of the appended claims. In the claims, any reference signsplaced between parentheses shall not be construed as limiting the claim.Use of the verb “comprise” and its conjugations does not exclude thepresence of elements or steps other than those stated in a claim. Thearticle “a” or “an” preceding an element does not exclude the presenceof a plurality of such elements. In the device claim enumerating severalmeans, several of these means may be embodied by one and the same itemof hardware. The mere fact that certain measures are recited in mutuallydifferent dependent claims does not indicate that a combination of thesemeasures cannot be used to advantage.

1. An electric lamp comprising: a lamp vessel (1) closed in a gastightmanner and provided with an illumination source (2), a centralcurrent-supply conductor (3) and a side current-supply conductor (4)issuing from the lamp vessel (1), a lamp base (5) for providing amechanical connection of the lamp vessel (1) and for providing amechanical and electrical connection of the central current-supplyconductor (3) and the side current-supply conductor (4), the lamp base(5) being provided with a notch (6) for passing through the sidecurrent-supply conductor (3) at a side facing the lamp vessel (1), theside current-supply conductor (4) being provided with a coagulateddroplet (7) of material of the side current-supply conductor (4) at aside facing away from the lamp base (5).
 2. An electric lamp as claimedin claim 1, characterized in that the coagulated droplet (7) is incontact with the lamp base (5).
 3. An electric lamp as claimed in claim1, characterized in that the coagulated droplet (7) is made by laserheating of a portion of the side current-supply conductor (4) issuingfrom the notch (6) in the lamp base (5).
 4. An electric lamp as claimedin claim 1, characterized in that the side current-supply conductor (4)is made from monel wire.
 5. An electric lamp as claimed in claim 1,characterized in that the lamp base (5) is made of aluminum.
 6. Anelectric lamp as claimed in claim 1, characterized in that the sidecurrent-supply conductor (4) is in clamping engagement with the notch(6) in the lamp base (5).
 7. An electric lamp as claimed in claim 1,characterized in that the notch (6) in the lamp base (5) iswedge-shaped.
 8. An electric lamp as claimed in claim 1, characterizedin that the notch (6) is provided in the lamp base (5) by means of lasercutting.
 9. A lamp base (5) for use in an electric lamp as claimed inclaim
 1. N:UserPublic(EAmendmentsNLO30414 prelim.doc 4